This is a large interdisciplinary program of investigation of the fundamental processes involved in immunologic vascular injury and disease. Studies under way include the physical, biochemical and physiologic properties of proteins, immunoglobulins, lymphocytes, macrophages and platelets. The methodology includes studies of the process of migration, proliferation, secretion, phagocytosis, degranulation, and division by these cells. Special attention is directed to genetic mapping (HLA and Ir loci) of subjects with a high incidence of certain diseases. Another group is evaluating the role of cyclic GMP in the regulation of cell function. The relationship between viral infection and immune response, with special reference to graft rejection, is evaluated by another group. The pathogenesis of immunologic vascular injury in the kidney is the major focus of another group of investigators.